Air bubbles or gas bubbles can accumulate in a pump assembly during operation, with the operation of centrifugal pump assemblies which for example deliver water from a well, as can be the case with house water systems. These accumulations for example can arise due gases dissolved in water being released. If the air or gas accumulations which have formed in the centrifugal pump in this manner become too large, then it can occur that the pump no longer delivers in the desired manner, i.e. that the throughput and pressure build-up are no longer given.